1. Field of the Invention
Aspects of the present invention relate to a lithium manganese oxide positive active material for a lithium ion secondary battery and a lithium ion secondary battery including the same. More particularly, aspects of the present invention relate to a lithium manganese oxide positive active material including a spinel lithium manganese oxide of three or more types of particles having different sizes, and a lithium ion secondary battery including the same.
2. Description of the Related Art
As applications of lithium ion secondary batteries are gradually extending from power sources for small-sized electric/electronic devices to power sources and power storage for large-sized electric/electronic devices such as electric vehicles, there is an increasing demand for a positive active material for a secondary battery having improved properties including high safety, long cycle life, high energy density and high power capability.
The lithium ion secondary batteries generally manufactured by providing a positive electrode and a negative electrode capable of reversibly intercalating/deintercalating lithium ions, and inserting an electrolyte into a space between the positive electrode and the negative electrode. The batteries produce and store electrical energy as a result of a redox reaction caused upon intercalating/deintercalating the lithium ions at the positive electrode and the negative electrode.
Various kinds of carbonaceous materials may be used as negative active materials of a lithium ion secondary battery, and lithium metal oxides may be used as positive active materials.
Specifically, spinel lithium manganese oxides are environmentally friendly and highly safe because they do not include heavy metals, such as cobalt. However, using the spinel lithium manganese oxide as the positive active material is considered problematic because of their low energy density per weight and volume of a layered lithium metal oxide.